Propeller



C. H. HAVlLL Nov. 5, 1935.

PROPELLER Filed June 25, 1934 2 Sheets-Sheet 1 Patented Nov. 5, 1935UNITED STATES PATENT OFFICE PROPELLER Clinton 11. Havill, East Orange,N. J., assignor to Eclipse Aviation Corporation, East N. 1., acorporation of New Jersey Application June 25, 1934, Serial No. 732,333

9 Claims.

speed may be readily limited irrespective of power,

air density or other conditions to which the aircraft is subjected.

Another object of the invention is to provide, in a construction of theabove character, a novel mechanism embodying a normally-circulatingfluid system entirely contained within the pro peller thus avoiding allfluid-sealing problems usually inherent in such mechanisms.

A further object is to provide, in a mechanism such as that indicatedabove and wherein a normally-circulating fluid system carried by thepropeller is employed, a novel mechanism whereby the circulation of thefluid is interrupted to permit a build-up of pressure to oppose afurther decrease in the pitch of the blades as soon as the speed ofrotation of the propeller has attained a predetermined maximum.

A still further object is to provide, in a variable pitch propeller ofthe above character, a novel centrifugally-governed device forinterrupting the circulation of fluid at a predetermined maximum speedof rotation of the propeller.

A further object is to provide, in a variable pitch propeller having aclosed circulating fluid system functioning to limit the maximum rate ofrevolutions of the propeller, a novel arrangement embodying a pump insaid system for circulating fluid therein together with connectionsbetween a stationary member and a propeller for operating the pump.

Other objects and novel features of the invention will appear more fullyhereinafter from the following detailed description when taken inconnection with the accompanying drawings, wherein one embodiment of theinvention is illustrated.

vIt is to be expressly understood, however, that the drawings areutilized for purposes of illustration only and are not designed as ad'efinitionof fonthis purpose to the appended claims.

the limits of the invention, reference beinghad several views: I Fig. 1is a side view, partly in section, of a propeller constructed inaccordance with the present invention;

Fig. 2 is an enlarged sectional view of a portion of the mechanism shownin Fig. 1, and

Fig. 3 is a vertical sectional view of the propeller shown in Fig. 1.

Referring more particularly to Figs. 1 and 2, a propeller constructed inaccordance with the present invention is illustrated therein as beingconstituted by a rotatable engine shaft or extension 10 thereof 5 and ahub 6 drivably connected thereto as by-means of a driving block 1 butrelatively movable longitudinally thereof in response to the thrustexerted by the blades, there being provided a plurality of bearings 8interposed between 15 the hub and driving block for more readilyenabling such movement of the hub. The latter is provided with aplurality of radially-extending sockets 9 adapted to rotatably receivethe inner or root ends of propeller blades I 0, there being 20 alsoprovided suitable link mechanisms H interconnecting the blades with aplate member l2 fixedly secured to the propeller shaft, these last namedmechanisms being effective to. vary the pitch of the blades during theaforesaid thrust- 25 for the purpose of arresting such movement at 30certain positions along the shaft in accord-- ance with the degree ofthrust exerted by the blades under the existing conditions of operation,there is preferably provided a plurality of resilient members, such asfor example coil springs 35 1 [3, arranged in a circle concentric withrespect to the shaft and having one end thereof bearing against a plateI 4 secured in any suitable manner to a forward extension l5 of drivingblock 1,

the other ends of said springs bearing against a 40 cylinder l5 carriedby the propeller hub and being provided for a purpose-which will appearmore fully hereinafter. It is to be noted that when the parts are in theposition shown in Fig. 1, the

pitch of the blades is a maximum, the pitch being 45 gradually reducedduring forward movement of the hub relative to the shaft in response tothe thrust of the blades, the above mentioned resilient members I3,however, serving to yieldably oppose such movement and to arrest the hubin such a position relative to the shaft that the pitch assumed by theblades will be substantially proportional to the thrust thereof and suchas to yield a substantially maximum propeller eiliciency for theconditions of thrust imposed.

One of the features of the present invention resides in the provision ofmeans for limiting the maximum rate of revolutions of the propeller andsuch means cooperate with the pitch-changing mechanism in such a mannerthat at a predetermined rate of maximum revolutions, further reductionin the pitch of the blades is prevented. In the form shown, such meansare fluid operated and include a normally-circulating cloud fluidsystem. Preferably, the system is carried entirely by the propeller andincludes a suitable gear pump I 6 comprising driving and driven gears l1and II respectively, the former being suitably driven by a stationarygear ll meshing with an elongated pinion 20. During rotation of thepropeller, the gear pump it pumps any suitable fluid such as oil, forexample, through conduit 2| which communicates with cylinder llsurrounding the propeller shaft. In this last named cylinder, a circularpiston element 22 concentric with the propeller shaft is disposed andsuch element, as shown, is secured to one end 01' pins 22' and 2|, eachof these pins being secured at the other end to the plate l4. As shownmore particularly in Fig. 2, a hollow screw 25 secures piston 22 to thepin 23 and the latter is provided with a passage 26 which conveys fluidfrom the cylinder I! to a fluid reservoir 21 by means of conduit 28 andpassages 29 and 30, there being a valvular element II disposed in saidlast named passage normally per mitting flow of fluid to said reservoir.

In order to conduct fluid from the reservoir 21 back to the pump IS, aconduit 32 communicates with the reservoir through passage 23 and alsocommunicates with a passage 34 provided in pin 24, this last namedpassage conducting fluid to a return conduit or duct 35 through a hollowmember 36 threadedly secured at one end thereof to the pin 24 andslidably received in a suitable aperture 31 in the propeller hub.

With the above named construction, it will be readily perceived thatduring rotation of the propeller, the pump I6 normally circulatesfluidthrough passage 2|, cylinder l5, passage 26, conduit 28, passages 29 and30 to the reservoir 21 and fluid from such reservoir is conducted backto' the pump through 23, 32, 34, I1 and return duct 35. As long as noobstruction is offered to the flow oi fluid, no pressure will be builtup in the cylinder l5 sufllcient to oppose relative movement between thecylinder I! carried by the hub and piston 22 carried by the propellershaft and change in pitch of the propeller blades may be readilyefiected.

Upon reduction in pitch of the blades, however, the rate of revolutionsof the propeller rises and in order to limit the maximum rate ofrevolutions in order tosecure maximum propeller and engine efliciency, acentritugally-operable mechanism is provided for obstructing the flow offluid in the above described. system. As shown, such means comprise thevalvular mechanism 3| which is slidably received in a cap 38 carried bythe forward portion of the engine shaft, such valvular mechanism beingnormally urged to the position shown as by means of a spring 39, thecompression of which may be varied by adjustment of screw 40. In theposition shown, the valve 3| establishes communication between duct 3.and reservoir 21 by reason of the cut-away portion II but as the speedof the propeller increases. this communication is gradually cut of! byoutward movement of the valve Si in response to centrifugal force. As

the valve moves outwardly under these conditions, communication betweenthe pump and res- 'der. ll.

ervoir 2! is gradually closed oi! and the pump gradually builds uppressure within cylinder II to offer an increase in resistance torelative movement between the cylinder and piston 22 during a furtherdecrease in the pitch of the blades. 5 This resistance graduallyincreases until communication between the pump and reservoir 21 isentirely shut on, at which time suflicient pressure will be built up incylinder I! to prevent a further decreasein the pitch of the blades. Asuitable by-pass valve 42 resiliently urged to its seat as by means oispring 43 serves to bypass the fluid around the valve ii to duct 44 inorder to limit the pressure which may be built up in cylin- Inoperation, thrust-responsive movement of the hub with respect to thepropeller shaft effects a reduction in the pitch of the blades throughthe link mechanisms -H and during such movement of the hub, the cylinderit will be moved to the right with respect to the stationary piston 22.The resilient means I I, as above stated, serve to resiliently opposesuch thrust-responsive movement of the hub and in normal operation, thehub will move forwardly and backwardly to decrease and increase thepitch of the blades in accordance with the thrust exerted thereby. Thefluid system including the gear pump has a normally-circulating flow offluid therein until such time as the valve 3| is moved in response tocentrifugal force to such a position as to obstruct the circulation offluid, whereupon pressure built up in cylinder l5 by continued operationof the pump I6 will prevent any further decrease in the pitch of theblades and hence will limit the maximum rate of revolutions of thepropeller.

While one form of the invention has been shown and described herein, itis to be understood that the same is not limited thereto but may beembodied in other forms as well known to those skilled in the art.Reference will, therefore, be had to the appended claims for adefinition of the limits of the invention.

What is claimed is:

1. In a variable pitch propeller having a plu- 45 rality of blades,means including a relativelymovable hub and shaft for automaticallyvarying the pitch of said blades during operation of the propeller,fluid pressure-operated means for limiting the reduction in pitch, andspeed-responsive mechanism for rendering operative said fluidpressure-operated means to limit said pitch reduction.

2. In a variable pitch propeller having a plurality of blades, means forautomatically varying 56 the pitch of said blades during operation ofthe propeller, fluid pressure-operated means independent of saidpitch-varying means for opposing further movement of said pitch-varyingmeans after the pitch of the blades has reached 60 a predeterminedminimum, and centrifugallyoperable mechanism for eflecting the operationof said fluid pressure-operated means to oppose further movement of saidpitch-varying means in the direction to reduce the pitch.

3. In a variable pitch propeller having a plurality of blades, means forautomatically varying the pitch of said blades during operation of thepropeller, fluid pressure-operated means indeo pendent oi. saidpitch-varying means for opposing movement of said pitch-varying means,and mechanism operable at a predetermined speed of rotation of thepropeller for effecting the operation of said fluid pressure-operatedmeans to 7 4. In a variable pitch propeller having a plurality ofblades, means for automatically varying the pitch of said blades duringoperation of the propeller, means independent of said pitchvarying meansand operable to oppose further movement of said pitch-varying means onlyafter the pitch of the blades has reached a predetermined minimum, andmeans responsive to the speed of rotation of the propeller at saidpredetermined minimum pitch for effecting the operation of said opposingmeans.

5. In a propeller of the type having a plurality of blades, and arelatively-movable hub and shaft, the pitch of the blades beingautomatically varied in accordance with such relative movementresponsive to the thrust of said blades, the combination with saidpropeller, of fiuid pressureoperated means for opposing thepitch-changing operation only after the pitch of the blades has reacheda predetermined minimum, and centrifugally-operable mechanism fordetermining the initiation of operation of said fluid pressureoperatedmeans.

6. In a variable pitch propeller having a plurality of blades, means forautomatically varying the pitch of said blades during operation of thepropeller, "fluid pressure-operated means independent of saidpitch-varying means operative for opposing a further decrease in thepitch of the blades only after a predetermined speed of rotation of thepropeller has been attained, and means responsive to centrifugal forceand operable at said predetermined speed for rendering operative saidfluid pressure-operated means.

7. In a variable pitch propeller of the type having a relatively-movablehub and shaft and means operable during such relative movement to varythe pitch of the propeller, a fluid pressure-operated pitch-limitingmechanism cooperating with said pitch-varying means and embody- 5 ing anormally-circulating fluid system, a pump in said system, and valvularmeans for interrupting circulation of fluid in said system whereby saidpump builds up pressure therein to oppose further change in pitch.

8. In a variable pitch propeller of the typev having arelatively-movable hub and shaft and means operable during such relativemovement to vary the pitch of the propeller, a fluid pressureoperatedpitch-limiting mechanism cooperating with said pitch-varying means andembodying a normally-circulating fluid system for limiting the reductionin pitch of the propeller, a pump in said system, and means responsiveto a predetermined speed of rotation of the propeller for interruptingcirculation of fluid in said system whereby said pump builds up pressuretherein to oppose a further decrease in pitch.

9. In a variable pitch propeller of the type embodying a plurality ofblades and a shaft drivably connected therewith, means for automaticallyvarying the pitch of said blades during operation of the propeller, andmeans for limiting the reduction in pitch of the blades comprising anormally-circulating fluid system, a pump in said system, and acentrifugally-operable valve mechanism effective at apredetermined'speed of rotation of the propeller for interruptingcirculation of fluid in said system whereby said pump builds up pressuretherein to oppose a further reduction in pitch.

' CLINTON H. HAVILL.

